Take-off and landing light units for airfield runways



Feb. 13, 1968 E. P. v. svENssoN ET AL 3,369,111

TAKE-OFF AND LANDING LIGHT UNITS FOR AIRFIELD RUNWAYS Filed Sept. 1, 1965 2 Sheets-Sheet 1 BY ,QM Q

E. P. v. SVENSSON ET AL 3,369,111

TAKE-OFF AND LANDING LIGHT UNITS FOR AIRFIELD RUNWAYS Feb. 13, 1968 2 Sheets-Sheet 2 Filed Sept. 1, 1965 14a 14b 14c I! I I\ 1 A Trd'E/Vf V5 United States Patent 6 F 3,369,111 TAKE-OFF AND LANDING LIGHT UNITS FOR AIRFIELD RUNWAYS Erik Patrik Viktor Svensson and Uno Nyberg, Stockholm, Sweden, assignors to Kgl Luftfartsstyrelsen, Stockholm, Sweden, a Swedish joint-stock company Filed Sept. 1, 1965, Ser. No. 484,256 9 Claims. (Cl. 240-1.2)

ABSTRACT OF THE DISCLOSURE This disclosure relates to a landing light for aircraft runways which is constructed so that the cover or roof thereof is level with the runway surface, the only part which extends upwardly being a reflector or a group of reflectors which serve to direct light from a source within the housing along paths at a slight elevation to the horizontal. The reflectors are resiliently mounted and thus automatically retract when struck by aircraft wheels or maintenance equipment, without damage to the structure.

Additionally, heat-conductive means are placed in the path of some of the light rays within the housing, these heat-conductive means being fixed to the cover and thus serving to melt snow thereon and prevent the accumula tion of snow and ice. A drain hole is provided at the base of the housing and additional heat-conductive means extend from position in the path of light rays into the drainage opening, thus assuring that snow or ice melted by the heated cover or roof and passing through the aperture through which the reflectors normally extend is maintained in the liquid state and discharged through the drain opening.

The present invention relates to illuminating installations for airfields and the like, and is more particularly concerned with take-off and landing lights for airfield runways.

It is a chief object of the invention to provide a take-off and landing light unit for mounting in such a manner that no stationary part thereof will protrude above the surface of the runway.

It is another object to provide a light unit which may take up any shocks caused by landing aircraft, without being damaged or unduly stressed.

It is a further object to provide a light unit which will, without additional heating means, melt away snow and ice which may tend to form thereon when used under severe climatic conditions.

A preferred embodiment of the invention will be described hereinafter with reference to the annexed drawings.

In the drawings FIG. 1 is a top plan view of a twin take-01f and landing light unit,

FIG. 2 is a cross section view along line I l-II in FIG. 1, and

FIG. 3 is another cross section view, along line IIIIII in FIG. 1, with the bottom structure shown in FIG. 2 removed.

The take-off and landing light unit illustrated in the drawings comprises a rigid grid-like structure which may be made of a steel casting, but which is preferably built up of flat, deep steel bars, within a circular housing 1 formed with a radially projecting flange 2 at its upper rim, adapted to receive a rigid flat cover 3 firmly attached to the flange 2 by fastening means, such as countersunk clamping screws (not illustrated).

The grid-like structure provided within the housing 1 comprises three deep, flat steel bars 4, 5, 6 in spaced parallel relationship, and two similar crossbars 7, 8 at right angles to bars 4, 5, 6 and made integral with the latter as by welding.

All bars 4 to 8 are joined to the housing 1 as by welding, so the latter with its flange 2 and the grid-like structure 4 to 8 form a rigid unit which may be mounted in a runway at the top of a concrete tube let into the ground and supporting. the housing 1 by the flange 2 thereof. This manner of mounting has not been illustrated, but is believed to be readily understood. When mounted in the ground the light unit should have the cover plate 3 flush with the surface 9 of the runway to be served by the light (FIG. 3). By this flush mounting, the light unit will not have any adverse or disturbing effect upon landing or taking off aircraft, and further it will not form any obstruction to snow-ploughs or other equipment used to clear the runways from snow or other deposits.

The twin light unit illustrated in the drawings comprises two identical single lights within a common housing, and it will clearly be suflicient by way of disclosure to describe one of these single lights.

In FIG. 2 there is illustrated a light source 10 secured by a bracket 11 to the bottom face of the cover 3 or to spaced strips 12 of highly heat-conductive metal, said strips being secured to the underside of the cover 3, making close contact therewith. The light source 10, which may be of any suitable type, known in itself, and comprising a housing enclosing an electrical lamp and a reflector,

covered by a front glass, is mounted with such an inclination that the light rays sent out thereby will have an upward elevation. The light rays emitted by the upper half of the light source are, however, intercepted by the bentdown end portions 12a of the strips 12, and also of bentdown portions 13a of further strip members 13, similar to strips 12 and like the latter attached to the underside of the cover 3. The crossbar 7 is recessed at its upper edge for the passage of strips 12. The purpose of strips 12, 13 is to have their temperature raised by their portions 12a, 13a absorbing the heat from the upper half of the light source 10. Heat absorbed by the strips will be conducted to the cover 3, and snow or ice at the upper face of the cover 3 will melt away under the influence of the heat thus provided.

' The light rays from the lower half of the light source 10 will pass through an aperture 8a in the crossbar 8, and will be caught by a reflector or mirror structure 14 comprising three mirror elements 14a, 14b and 140, respectively, which extend upward through corresponding apertures 15a, 15b and 15c in the cover 3 (FIG. 1). The mirror elements may have a plane or curved reflecting surface, and their tops are substantially level with the upper face of .the cover 3. They leave parts of the apertures free, to permit the passage of the light rays. The mirror structure 14 comprises a base plate 16, and this base plate 16 is supported by guide rods 17 rigidly secured to the cover 3 and projecting downward, and is urged upward by compression springs 18 encircling the rods and abutting adjustable nuts threaded onto the rod end portions. Adjusting screws 19 passing through the mirror base plate 16 and engaging the underside of the cover 3 are provided for setting the base plate at such a height and with such an inclination as required to give the desired reflected illumination.

Through the resilient arrangement of mirrors 14a, 14b,

140, the latter may move away when subjected to a pres creases gradually towards the outer rim of the cover, whereas the width of each groove increases in that same direction. The mirror elements 14a, 14b, 14c might be united into a single mirror, and the apertures 15a, 15b, 150 would then have to merge into a greater common aperture from which a single groove with a greater width might extend. The structure would become mechanically weaker in such case, however, and would admit more moisture and foreign particles than the preferred embodiment illustrated. The grooves are disposed opposite the strips 12 at the underside of the cover whereby snow and ice lying upon the cover 3 will melt away from the grooves, in the first place. The melt-water (as well as rain-water) is conducted by the inclined bottom of the grooves to the apertures 15a, 15b, 15c and drops through the latter, to be drained off in a manner to be described later.

The mirror elements 14a, 14b and 140 are secured to the base plate 16 at such an inclination, that, after possibly needed adjustment of the screws 19, the central rays 21 from the light source are reflected as rays 22 with a very slight upward elevation, for example substantially parallel to the bottom of the grooves 20a, 20b and 206. The nethermost peripheral light rays 23 caught by the mirrors are reflected as rays 24 with the highest elevation. Those rays emitted from the lowermost part of the light source strike a highly heat-conductive shield member 25, preferably of sheet metal.

This shield member 25 extends downward into or through a drain hole 27 at the lowest point of a sheet metal tray 26 attached to the housing 1 (FIG. 2). This tray 26 will collect water and moisture which has penetrated into the housing, and will conduct such water to the drain hole 27. The heat absorbed by the shield member 25 will melt any ice formed in the drain hole 27 which thus is always kept clear when the light unit is operating.

The take-off and landing light units according to the invention are preferably mounted in spaced relationship along the center line of the runway to be served. By the arrangement of the light source 10 and the reflecting mirrors 14a, 14b, 14c described above, the central light rays 21-22 which are those rays having the greatest intensity, are reflected nearly parallel to the runway surface, and the intensity of the light rays having a greater elevation decreases progressively, to attain its least value for the rays 23-24 from the lowest unobstructed part of the light source. It is of vital importance for a pilot of a taking-off or landing aircraft that he will be able to see as many of the lights at the same time as possible, subject, of course, to visibility conditions and the actual power of the lights. It is obvious that the pilot will be better and more safely guided the greater number of lights he will be able to observe at any given moment. The lights should have such an intensity distribution that the pilot can see both distant and close light without being dazzled or otherwise disturbed. To satisfy this requirement the intensity distribution of the observed light should be such, that the light emitted at the lowest elevation should have the greatest intensity, that which will give a long reach, whereas the light intensity should decrease gradually with increasing elevation of the emitted light rays, and should be lowest for the light rays having the greatest elevation and the shortest reach. These requirements are met by the lights according to the invention.

The cover 3 may be made in one :piece, but in the embodiment illustrated it comprises several pieces which may be removed individually when performing main- 'tenance work or repairs to one or other of the twin lights. By making the cover in several parts also the dissipation of heat to portions of the cover for which the removal of snow or ice is not as urgent as for the apertures and grooves is reduced.

The light unit illustrated will send out light rays along two straightly opposed directions. It lies, however, completely within the scope of the invention to provide single light units, or twin lights sending out their light rays in directions which are not straightly opposed, but extend in angular relationship to each other, and it will be readily understood by those skilled in the art how any such modifications may be effected.

What we claim is:

1. A take-off and landing light unit for flush mounting in the runways of airfields and the like, comprising a rigid housing, rigid flat-shaped detachable cover means therefor, and at least one light source disposed therein, to emit a bunch of light rays in an oblique upward main direction, reflector means, said reflector means being supported within said housing to catch at least a substantial portion of the light rays emitted, there being at least one aperture in said cover means for receiving in a portion thereof at least part of said reflector means, said cover means being further formed with at least one elongated groove in the upper face thereof, said at least one groove extending away from said at least one aperture and having its greatest depth adjacent thereto, said depth gradually decreasing with the distance from said at least one aperture, said at least one groove permitting the passage of reflected light rays near-parallel to the runway surface, resilient support means for said reflector means to urge the latter into an operational upper position, and adjusting means for setting said reflector means in operational position.

2. A take-off and landing light unit for mounting flush with the surface of runways belonging to airfields and the like, said unit comprising a rigid housing structure and detachable rigid flat roof means therefor, a light source being provided within said housing structure so as to direct a bunch of light rays obliquely upward, reflector means adapted to receive at least part of said light rays, said roof means being apertured for receiving an upper portion of said reflector means and for permitting the passage of incident and reflected light rays, upward facing groove means in said roof means for the passage of reflected light rays in a slightly upward direction, heatconductive means attached to the underside of said roof means and having portions extending into said bunch of light rays to be heated thereby, drainage means at the bottom of said housing structure, outlet means from said drainage means and a shield member of heat-conductive material positioned in front of said light source to intercept a portion of the radiation therefrom, said shield member extending into said outlet means.

3. A take-off and landing light unit for mounting flush with the surface of airfield runways, said unit comprising a housing, a relatively deep grid-like frame structure disposed within said housing and rigidly connected to the wall thereof, said housing wall being formed with horizontally extending flange means at the upper rim thereof, detachable flat-shaped cover means, said flange means and said grid-like frame structure forming a support for said cover means, said cover means comprising at least one apertured portion and having groove means formed in the upper face thereof, said groove means having an upward bottom inclination from said at least one apertured cover portion, at least one light source disposed within said housing, means for mounting said at least one light source at the underside of said cover means to send out a bunch of light rays obliquely upward, highly heat-conductive metal strip means being tightly attached to the underside of said cover means opposite said groove means, said metal strip means being formed with depending portions, said depending strip portions projecting into the bunch of light rays from said at least one light source, to intercept and absorb a substantial portion of said light rays, reflector means disposed at least partly within said at least one apertured cover portion for catching and reflecting incident light rays from said light ray bunch, said groove means permitting the passage of reflected rays almost parallel to the ground, means for supporting resiliently said reflector means in an operative upper position, and adjusting means for setting said operative position.

4. In a take-off and landing light unit as claimed in claim 3, the provision of tray means at the bottom of said housing, said tray means comprising draining means, and a shield member of highly heat conductive material for the lowermost portion of said at least one light source, said shield member extending at least into said draining means.

5. A take-off and landing light unit as claimed in claim 4, wherein the side walls of said groove means diverge away from said at least one apertured portion.

6. The combination of two take-off and landing light units as claimed in claim 5 within a common housing, said light units being mounted to send out their respective light rays in opposed directions, for serving a runway in both lengthwise directions.

7. In a take-01f and landing light installation for an airfield runway, the provision of combination light units as claimed in claim 6, said combination light units being disposed in spaced relationship along the center line of said runway.

8. A take-01f and landing light unit for mounting flush with the surface of an aircraft runway, comprising, in combination, a rigid housing structure having a detachable fiat roof, a light source within said housing structure, reflector means for directing rays from said light source outwardly through an aperture in said roof at a slight angle to the horizontal, and heat-conductive means fixed to said roof, said means comprising strips having portions thereof bent therefrom and extending into the path of light rays from said source, said heat-conductive means serving to heat said roof and prevent the formation of ice thereon.

9. A take-off and landing light unit in accordance with claim 8 wherein said housing is provided with a drain hole at the base thereof and wherein additional heatconductive means are fixed in said housing extending into the path of light rays from said source, said heat-conduc tive means extending into said drain hole to thereby prevent formation of ice therein, thus assuring melting of ice and snow from said roof and discharge of water through said aperture and said drain hole.

References Cited UNITED STATES PATENTS 2,984,735 5/1961 Batterson 2401.2 3,096,024 7/ 1963 Young 2401.2

FOREIGN PATENTS 232,910 2/1961 Australia. 759,848 10/ 1956 Great Britain. 896,202 5/ 1962 Great Britain. 863,597 1/1953 Germany.

NORTON ANSHER, Primary Examiner.

DAVID L. IACOBSON, Assistant Examiner. 

